Flotation apparatus



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Patented Apr. 12, 1927.

UNITED STATES PATENT orr'lcs.

TOM H. OWEN, OF WALLACELAND MIOHAEL I. DALTON, OF MULLAN, IDAHO.

I'LOTATION arrane'rns.

Application flied July 5,

Our invention is an improved apparatus for the flotation concentration of 0r es,- but has utility for other processes wherein it is necessary to agitate or aerate, or both agitate and aerate a body of liquid or of mixed liquid and solids. In the practice of the flotation rocess by the mechanical agitation in fact almost invariably, desirable to subject the ore pulp to agitation in a considerable number of separate agitation cells. This lnvolves the necessity of providing some means of conveying the pulp from cell to cell and maintaining it at the proper level in each cell. IVhere the conformation of the land admits it is often convenient to effect this purpose by placing the cells successively at a lower level and initially supplying the pulp to the uppermost cell. It frequently happens however, that it is necessary or advantageous to build all of the cells upon the same level.

In some flotation plants individual motors are provided for propelling the agitation mechanism of each cell, the agitator shafts in cells of this type generally being vertical. Our invention is designed as an improvement in the type'of machines wherein the agitators are mounted upon a horizontal shaft. The length of a single cell provided with such a horizontal shaft or the number of such cells which can be placed in series. and operated by a single'shaft is limited by the practical length of shaft that can be used without resulting in injurious whipping and vibration. In our improved apparatus, we

provide a plurality of bearings for the horizontal shaft, these bearings being placed in spaces from which the pulp is excluded, suchspaces being conveniently provided in the form of the apparatus illustrated by a suiiicient separation of the successive eel s to rovide spaces therebetween to accommodiite the necessary bearings, and we provide for the moving of the pulp from cell to cell by mounting elevators upon the shaft, whereby the pulp is elevated sufficiently to impart the necessary flow by gravity. By-

means of this arrangement we are enabled to place all of the cells on one level and to provide the agitator and elevator shaft with as many bearings as necessary to insure practically vibrationless operation. A series of cells so constructed can be extended to 1824- Serial No. 724,250.

it is practical to carry the diameter of the shaft in order to properly transmit the torque.

In the drawings: Figure 1 is a plan View, with certain details omitted, 0 three flotation cells embodvlng my invention.

figure 2 is a plan view upon an enlarged scale of one of the cells shown in Figure 1. Figure 3 is a transverse sectional view upon the line 3-3 of Figure 2.

Figure 4' is a transverse sectional view upon the line 44 of Figure 2.

Figure 5 is a longitudinal sectional View of one of the conical deflectors fixed to the shaft at the points where it passes through the walls of the cells.

Figure 6 is a transverse section taken on line 6-6 of Figure 2.

Figure 7 is a transverse section on line Figures 9 and 10 are respectively cross sectional views on lines of Figure 2.

As illustrated 99 and 10-10 to the cell 1', shown at the right, this being the head oi the machine. As shown herein the three cells 1, 2 and 3, are similar except in the fact that cell 1 is not provided with any elevator mechanism, the pulp being initially delivered to that cell from some outside source. Manifestly the initial cell may also be provided with an elevator, if desired. At ,the head end of the second and third cells, we show elevator chambers 44 and the agitator or impeller chambers G. In the form shown each cell is divided into two compartments, g-g, by means of a partition 5. In practice, the number of partitions may vary or be entirely dispensed with but in most instances one or more such partitions are advantageous in order to get otter control of the differing grades of concentrates.

Referring to Figure 1, it will be observed that we have provided bearings for the main. shaft 6, at 7 and 8, these two bearings being located at the head end of the machine;

in Figure 1, the pulp is' initially delivered by any suitable means at 9 and 10, between the cells 1 and 2. and 2 and 3 respectively; and at 11., the tail end of the machine. This shaft may be oper- 'ated from any suitable source of power as dicated in Figure 6, the front wall 16, opposite the agitator rotor extends upwardly to a point somewhatbelow the level of the axis of the shaft and there carries an inclined apron 17 provided at its upper edge with a vertical lip 18 over which the concentrate froth flows into the launder 19. The height of front wall 16, the presence or absence, and the size of -members 17 and 18 are preferably controllable at will to suit the requirementsofi the pulp under treatment. By the use of members 17 and 18 as shown in Figure 6 we get the effect of a spitz-box with a constricted lip the amount of constriction depending on the length of member 17.

The transverse partition 5, as indicated in Figure 4:, is provided with an opening 20, extending across and immediately adjacent the bottom of the cell. Mounted upon the shaft 6, are elevator and agitator rotors, said agitator rotors being provided in all of the cells and elevator rotors in such of the cells as desired. As shown herein elevator rotors are provided in each of the cells after the first. The agitator rotors are preferably mounted in each agitator compartment, such rotor being shown in transverse section in Figure 6 and consisting of a pair of spaced pulleys 21, 21 or the like upon the rims of which are afiixed a series of longitudinal strips 22, separated by intervening spaces 23. The elevator compartment 4 is relatively short and contains an elevator rotor of construction similar to that of the agitator rotors, but consisting of but one pulley member, so it is of less length longitudinally of the shaft. The construction of the elevator rotor is shown in Figure 7 and comprises the pulley 24 upon the periphery of which there are, mounted a series of longitudinally extending angle irons 25, separated by intervening spaces 26.

txtendin over the entire top of each cell, (see Fig. 63 is a hood 27, at the front of which is a depending vertical wall 28, which terminates. below the level of the shaft 6, and of the over flow lip 18. it vertical baflle 29. has its upper part between the depending wall 28 and the periphery of the agitator rotor. The agitator rotor revolves in the direction indicated by the arrow 32, and throws the pulp upward and forward as indicated by the arrows 30 and at the front of the cell the pulp passes through the space 31 into the spztz-box K as indicated by the arrow at that point. The lower edge of the In the front of the baffle 29 is spaced above the floor of the cell.

over the lip 18 being received in the launder 19 and discharged through the duct 35.

The distribution of parts in the elevator chambers 4, is clearly shown in Figure 7. elevator chamber, the front wall 16 extends to the'top of the machine instead of terminating at a discharge apron l7, as described in connection with the flotation chambers. At some distance inside of the front wall 16, the elevator chamber is provided with a wall 36, which extends upwardly from the floor parallel to the shaft 6 and is provided at its upper edge with an apron 37 which inclines toward the elevator rotor and terminates in immediate proximity thereto.

Pulp delivered to the bottom of the ele vator chamber is -thrown upward by the revolution of the elevator rotor and is thrown forwardly into the space between walls 36 and 16 as indicated by the arrows 60.

The pulp consisting of water carrying the usual proportion of powdered ore in suspension is delivered to the head end A of the apparatus. Cell 1, as herein shown, may be employed primarily as a mixing cell for the dissemination of the flotation agents throughout the body of pulp and for giving it a preliminary agitation and aeration. No elevator mechanism is ordinarily necessary in such a mixing cell, for the reason that the pulp is usially delivered to that cell from a suitably arranged outside source. Cell 1 is constructed substantially the same as the agitator cells differing only in minor details, as will subsequently appear. Its construction is shown in Figure 8 which is a sectional view through cell 1 used as a mixing cell. Ordinarily, by reason of the adjustment of the pulp level in the first cell and the fact that the pulp does not become thoroughly aerated at this early state of its treatment, a comparatively small amount of froth, sometimes practically none, overflows the lip 18 of cell 1, but provision is made for receiving such froth as may overflow, cell 1 being fitted with a launder 19 like those on the following cells. Thepulp supplied thereto flows to the bottom, where it .is caught by the peripheral bars 22. of the agitator rotor and thrown upward and forward through the space 31 into the spitzbox K formed between the front wall 16 and the depending wall 28 and bafile 29.

Ln I retained in t Some of the pulp is carried completely around the periphery of the rotor, the proportion between the amount carried around the rotor and that fldwing to the spit-z-box through space 31 depending on the speed of rotation of the rotor and the relation of the parts of the machine.

In case the level of the pulp and the amount of froth formed in the mixing cell are such as to cause an overflow of froth over the Ii 18, the froth concentrate is col lected in t e launder 19. The bulk of the pul however, returns from the Spitz-box K to t 1e main body of the mixing cell through the opening 33 whence it is again thrown upward, thus 7 c cle above described as it proceeds from tl ie head end of the cell toward the tail end. It is observed that the battle 28' is moved further away from 29 thus making the space 31 larger than the corresponding space 31 in the ordinary agitator cells. In this way the pul in the spitz-box is subjected to a severe iiammerin by the pulp circulated through 31 by the rotor and little if any froth is )ermitted to form. Furthermore the s itzox is preferably divided into a plura ity of spaces 16 16 by rovision of three vertical bafiles- 17 17". hese bafiies delay passa e of'pulp by deflecting it back to the rotor ciamber through 33". A cover 20 is also rovided to prevent stuff falling into the SPltZ-bOX. At the tail end of the Spitz-box of the mixercell 1 there is an opening B in the end wall immediately above the floor of the cell. This opening B leads to a box E one side of which is formed by a vertically adjustable weir 40 as shown in detail in Fi ure 9. The height of said weir is preferably adjusted by adding or removing thin slatsof wood 40'. 40- or like material, these slats fitting into grooves 40 40 at each end of the slats. The level of the upper edge of the weir 40 determines the level at which the pulp is maintained in the preceding cell, or, more roperly, determines the amountof ulp wiich atany moment is iiat cell. By reason of the rapid revolution of the rotor the pulp is kept in a constant state of circulation and is not permitted to settle to a definitely defined level. The pul which overflows the weir 40 enters a box I just behind the chamber E and formed between the weir 40 and the vertical back wall 80 separating the chamber F from the bearing space. The chamber F is connected by an opening C at the floor level of the elevator chamber 4 of the next cell.

Referring now to the action in the elevator chamber, shown in Figure-7 the pulp therein is dashed upward b the elevator wheel and falls forward of t e partition 36 and apron 37 as indicated by the arrows 60 upon Figure 7. Falling to the bottom of the space between the front wall 16 and the repeatedly going through the.

partition 36, the pulp flows into the next cell through an opcnlng I) which is forward of the wall 36, and preferably near the bottom of. the cell. The opening D can be atmthe front of the wall 36; as shown herein, said opening is adjacent the bottom of the cell,

. butit could be raised, if desired by insertin a false bottom and bringing it to the helght f the false bottom. The outlet 1) prefer-ab y leads into a com artmcnt 89 formed by'theend of the eel 15, to wall 2}), the part of the spitz 16, and a vertual partition 90. The pulp ets out of this box through an extension of opening 33 and thence into the rotor or a itator chamgir. This compartment is fitte with a cover 'It will be observed that by the construction above described the weir 40 defines the lower edge of a duct at a predetermined and adjustable level for the flow of pulp into the elevator chamber, and that the vertical wall 36 a d apron 37 (Fig. 7) establish an outlet. duct from the elevator chamber at the level of the upper edge of apron 37, this outlet duct being at a level higher than the inlet duct in any of the positions to which weir 40 is adjustable. The weir 40 therefore re ulates the pulp level in the cell preceding 1t. Means are thus provided for,maintaining any relative )ulp levels in the different cells that may be esirable in the operation of the ap aratus.

n cell 2 the pulp is dashed upward and forward by the rotor as explained in connectionwith Figure 6 of the drawing in the above description of the operation taking place in the first or mixer cell. The pulp proceeds from, the head end to the tail end of the second cell, during its course being repeatedly dashed upward and and through the space 31 into the Spitz-box K where the concentrate froth overflows the lip 18, the body of the ulp returning through the opening 33 to be. again circulated through the same cycle by the rotor. The partitions 5 serve to retard the flow of ulp through the cell, the size of the .opening 20 (Fi ure 4) being insufiicient to permit such rapi flow of the pul as would permit it to escape with insu cient agitation. At the foot of this cell the construction pro-. vided for maintaining the level of pulp by an adjustable weir 40 and conducting it to the next cell is the same as described above in connection with the mixing cell.

As will be a parent from Figures 1 and 2, the boxes F and E throughwhich the pulp flows over the weir 40 are located forward of the shaft 6 thus leaving suflicient space between the successive cells atthe rear of these boxes for the mounting of shaft bearings between the ends of adjoining cells. Such bearings are shown at 9 and 10 in Figure 1, and the bearing 9 is shown upon an enlarged scale in Figure 2. In order to prevent the pulp from passing through the openings in the end walls of the cells through which the shaft passes we have provided deflectors and cover plates therefor, shown in detail in Figures 2, 3 and 4. In Figure 5 is shown in a detail sectional view the manner in which the deflectors and cover plates are mounted;' The deflector 43 comprises a hollow cylindrical part 44 and two annular conical flanges 45 and 46 which diverge from the shaft in a direction toward the interior of the cell. The member 43 is fi.ced to the shaft by a set screw or otherwise, the cylindrical part 44 lying within a circular opening in the end wall 'of the cell. fixed to the inner face of the end wall is the cover plate 47. This cover plates comprises a flange 48 which lies against the end wall and is bolted thereto, an outwardly extending conical section 49 and a flat top 50. InbperatiQn the amount of pulp in the cell is not sufficient to cause it to pour through the opening 51 around the shaft 6, but the pulp is being constantly dashed upward by the rotor and it is necessary to pro vide means for preventing that part of the pulp which is dashed against the end wall and shaft from passing out. through the opening 51. That part of the pulp which lodges upon the shaft 6 is arrested by the flanges 45 and 46 and caused to drop back into the cell, and the direct precipitation of pulp against the end wall around the openlug-51 and against the deflector 43 is prevented by the cover plate 47. Ve have shown this cover plate 47 as provided with-a slot 52 at the lower side to permit any pulp that is deflected by part 43 to flow back into the cell. \Ve have also shown in Figure 2 collars 53, one of which is preferably fixed to the shaft 6 at each side of each of the bearings 9 and 10 in order to constitute a further safeguard against the entrance of pulp into the bearings.

By the means above described we provide an alined series of practically any necessary number of flotation cells upon one level, all operated by a single shaft, and with suflicient shaft bearings to prevent whipping or objectionable vibration. The elevators pick up and move the pulp at a rate sutiicient to keep the pulp level lower upon the discharge sides of the wcirs 40 than upon the head sides thereof, thereby causing the pulp to flow freely from cell to cell, and by adjustment of the weirs means are pro-. vided for accurately and independently adjusting the level of pulp in each of the cells. The use of elevators of the type described makes it possible to treat comparatively coarse sand particles. \Vithout such elevators the operation of the apparatus would be confined to finely pulverized ore that would flow naturally from cell to cell. The

elevators, besides their function of lifting the pulp and moving itfrom cell to cell, act as agitators and assist in the aeration of the pulp and the mixing of re-agents therewith. The possibility of maintainin the pulp level independently in the diti erent cells renders the machine especially adaptable for taking oil ditl'crent concentrates in different cells. Reagents of different kinds and in diifereut amounts can be added 'in the different cells and this in connection with the possibility of independently regulating the level in the Spitz-box K of each cell renders the apparatus especially adaptable for selective flotation.

While our improved apparatus can be op- .erated without the elevators while retaining other advantages above described, such mode of operation is generally undesirable for the reason that without elevators the level of the pulp is higher at the head end of the machine than at the tail end, and this is opposed to the condition ordinarily desirable. Ordinarily froth is formed more abundantly near the head end of the machine, the pulp at this time containing all Of'llllG flotation material, whereas the more or less depleted pulp at the tail end of the machine gives rise to a less abundant froth, thereby generally rendering it desirable to maintain a higher level in the cells near the tail of the machine. Upon reference to Figure 6 itwill be apparent that the area on which froth forms can be readily enlarged or restricted according to the re quircments of particular ores as for instance by moving the apron 17 with its lip 18 toward the front or back of the machine to widen or narrow the area upon which froth forms or by the use of pointed choke boxes 95, of the usual form, thus affording means of controlling the operation of the apparatus and the depth of the froth layer.

The com )lete enclosure of the apparatus. by the hooc 27, depending wall 28 (Figure 6) and the external walls of the cells is advantageous in that with certain flotation agents, including gases the air in the cells becomes highly charged with ,vaporized or gaseous re-agent. By confining this charged air to the apparatus the objectionable diffusion and loss of vaporized agent is to a great extent prevented and the re-agentcharged air is utilized for froth function. The openings 51 in the cell walls through which shaft 6 passes (Figure 5) provide sulliciently for the entrance of air to the cells, and the air so entering finds its way to the pulp through the openings 23 and 26 between the bars 22 and 25 of the agitator and elevator rotors.

In some cases we have passed the air in through a series of relatively small holes bored in the top sections of the hood 27 and a certain amount of air finds its way in A through the inlet space formed by 90. When desired air can be admitted under slight pressure.

We claim as our invention:

1. A flotation apparatus comprising an aligned series of cells, each consisting of an impeller chamber, and an elevator chamber communicating with the head end of said impeller chamber at its bottom, a shaft extending lengthwise of said cells, impellers and elevators mounted on said shaft and within said impeller and elevator chambers respectively, and discharge ducts connecting the tail end of each impeller chamber with the followin elevator chamber, and means for maintaining the pulp level at the intake to each elevator chamber substantially lower than at the discharge therefrom.

2. A flotation apparatus comprising an aligned series of impeller chambers disposed on the same level, elevator chambers lntermediate said impeller chambers, an elevator in each elevator chamber, discharge ducts connecting each impeller chamber with the following elevator chamber, and a weir in said ducts for -maintai'ning a relatively higher pulp level in each preceding impeller chamber than in the following elevator chamber.

3. In a flotation apparatus, a flotation cell, a horizontal shaft extending through said cell, a partition extending across said cell transversely of said shaft, said partition being provided with an pening to receive said shaft and forming impeller and elevator chambers in said cell, a cylindrical impeller and a cylindrical elevator mounted on said shaft insaid impeller and elevator chambers respectively, a spitz box communicatin wit-h said im eller chamber and also said elevator cham er communicating with'said impeller chamber through a duct having a relatively high level and thence through an opening adjacent the bottom of said partition.

4., In a flotation apparatus, a flotation cell,

a horizontal shaft extending through said cell, a partition extending across said cell transversely of said shaft, said partition being provided with an opening to receive .said shaft in said impeller and elevator chambers in said cell, a cylindrical impeller and a cylindrical elevator mounted on said shaft in said impeller'and elevator chambers respectively, a spitz. box communicating with said impeller chamber at two different levels and also communicating with said elevator chamber through a duct at a level higher than said spitz box.

5. A flotation apparatus comprising an alined series of alternating impeller and elevator chambers disposed upon the same level, a shaft extending through said series of chambers, impeller and elevator means actuated by said shaft in saidimpeller and elevator chambers respectively, spitz boxes communicating with said impeller chambers, a duct communicating from a relatively high level in each of said elevator chambers to the succeeding impeller chambers and a duct communicating from each of said impeller chambers to the succeeding elevator chambers having means therein for controlling a normal level of ore pulp in its respectlve impeller chambers and spitz box.

6. A flotation apparatus comprising an alined series of alternating impeller and elevator chambers disposed upon the same level, a shaft extending through said series of chambers, rotary impeller and elevator means actuated by said shaft in said impeller and elevator chambers respectively, spitz boxes offset forwardly of said shaft on one side of said impeller chamber-sand communicating therewith, a relatively high partition in each of said elevator chambers offset forwardly of its respective elevator, and forming a passage having communication with the succeeding impeller chamber, and a duct communicating from each of said impeller chambers to the succeeding elevator chambers having means therein for controlling the normal level of ore pulp in its respective impeller chamber and spitz box. I

'7. A flotation apparatus comprising an alined series of cells disposed upon the same level and adapted to contain an ore pulp, bearing spaces between some of said cells, a shaft extending through openings in said series of cells, bearings for said shaft in said bearing spaces, means permitting passage of. air in and out of said cells, adjacent said shaft opening but excluding ore pulp from said bearin spaces and means driven by said shaft for agitating said pulp and for moving the same from cell to cell.

8. A flotation apparatus comprising an alined series of alternating impeller and elevator chambers disposed upon the same level, a shaft extending through said series of chambers, impelling and elevating means actuated by said shaft in said impeller and elevator chambers respectively and a duct connecting successive impeller and elevator. chambers having an adjustable weir therein for controlling the level in the preceding impeller chamber.

Signed at Wallace this 25th day of June,

TOM M. OWEN. MICHAEL P. DALTON. 

